Bender J G, Van Epps D E, Chenoweth D E
Department of Pathology, University of New Mexico, School of Medicine, Albuquerque 87131.
J Immunol. 1987 Nov 1;139(9):3028-33.
The fluoresceinated chemotactic factors, C5a, formyl-methionyl-leucyl-phenylalanyl-lysine (FMLPL), and casein were used in conjunction with flow cytometry to examine chemotactic factor receptor expression on polymorphonuclear leukocytes (PMN) activated with phorbol myristate acetate (PMA), C5a, or formyl-methionyl-leucyl-phenylalanine. Activation with PMA resulted in a dose-dependent increase in binding of fluorescein-labeled (FL)-casein and (FL-FMLPL) over the range of PMA concentrations from 0.5 to 50 ng/ml. In contrast, activation of PMN with PMA resulted in a dose-dependent decrease in FL-C5a binding, and activation with concentrations above 5 ng/ml resulted in a complete loss of binding. This loss of binding was not caused by inactivation of the ligand or prevented by the addition of superoxide dismutase and catalase or protease inhibitors. Furthermore, incubation of PMN with supernatants from PMN stimulated to degranulate did not reduce the availability of C5a receptors. This pattern of increased FMLPL and casein binding with decreased C5a binding was also observed with cytochalasin B-pretreated PMN that were stimulated with chemotactic factors. Parallel studies of superoxide anion generation demonstrated that PMA-treated PMN were still responsive to formyl-methionyl-leucyl-phenylalanine, but not to C5a. These data demonstrate that the activation of PMN up-regulates formyl peptide and casein receptors whereas C5a receptors are down-regulated under similar conditions.
将荧光素化趋化因子C5a、甲酰甲硫氨酰亮氨酰苯丙氨酰赖氨酸（FMLPL）和酪蛋白与流式细胞术结合使用，以检测经佛波酯（PMA）、C5a或甲酰甲硫氨酰亮氨酰苯丙氨酸激活的多形核白细胞（PMN）上趋化因子受体的表达。用PMA激活导致在0.5至50 ng/ml的PMA浓度范围内，荧光素标记（FL）的酪蛋白和（FL - FMLPL）的结合呈剂量依赖性增加。相比之下，用PMA激活PMN导致FL - C5a结合呈剂量依赖性减少，且浓度高于5 ng/ml时激活会导致结合完全丧失。这种结合丧失不是由配体失活引起的，也不能通过添加超氧化物歧化酶、过氧化氢酶或蛋白酶抑制剂来阻止。此外，将PMN与刺激后脱颗粒的PMN上清液孵育不会降低C5a受体的可用性。在用趋化因子刺激的细胞松弛素B预处理的PMN中也观察到这种FMLPL和酪蛋白结合增加而C5a结合减少的模式。对超氧阴离子生成的平行研究表明，经PMA处理的PMN仍然对甲酰甲硫氨酰亮氨酰苯丙氨酸有反应，但对C5a无反应。这些数据表明，PMN的激活会上调甲酰肽和酪蛋白受体，而在类似条件下C5a受体则被下调。
